Export log as .CSV file not working

Not sure what that could be. You need to be logged in as the wordpress admin. Your system needs to have either wp-load.php or wp-config.php in the normal place (2 directories above your EBD directory .. in the wordpress root). Those are the main requirements.

You probably need to have some data, so you need to do a couple of test downloads so that there is some csv data to export.

Beyond that, not sure what it could be. The export.php is pretty short, not much can go wrong. Suggest you check all your error_log files (PHP error logs) to see if the problem is getting killed due to some php error.